<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>键盘事件</title>
    <style>
        #result{
            width: 500px;
            height: 400px;
            border:solid 1px #666;
        }
    </style>
</head>
<body>
    <div id="root"> </div>

    <script src="../js/react.development.js"></script>
    <script src="../js/react-dom.development.js"></script>
    <script src="../js/babel.min.js"></script>

    <script type="text/babel">
        class App extends React.Component{

            state = {
                msgs: [
                    '愿时光能缓，愿故人不散！',
                    '我希望兜兜转转之后那个人还是你'
                ]
            }

            render(){
                return <div>
                        <input type="text" onKeyDown={this.handleKeyDown} onKeyUp={this.handleKeyUp} /> <button>敲回车显示内容</button>
                        <hr />
                        <div id="result" ref={el => this.result = el}>
                            <ul>
                                {
                                    this.state.msgs.map((item, index) => {
                                        return <li key={index}>{item}</li>
                                    })
                                }   
                            </ul>    
                        </div>
                    </div>
            }

            handleKeyDown = (e) => {
                // console.log('down', e.target.value);
                //获得当前的按钮信息   键码
                if(e.keyCode === 13){
                    //获取当前 input 的输入值
                    let v = e.target.value;
                    //方式一 向 msgs 中压入数据
                    // let {msgs} = this.state;
                    // msgs.push(v)
                    // //调用 setState
                    // this.setState({
                    //     msgs: msgs
                    // })

                    //方式二
                    this.setState({
                        msgs: [...this.state.msgs, v]
                    })
                }
            }

            handleKeyUp = (e) => {
                // console.log('up', e.target.value);
            }
        }

        ReactDOM.render(<App />, document.querySelector("#root"));
    </script>
</body>
</html>